At Wunderlich, we have an open ear for our customers. Of course, this also applies to the drivers of the BMW R 1250 GS and R 1200 GS LC, who are undoubtedly among the best all-round motorcycles. One point that is always addressed is the clearly perceptible, low-frequency roar of the two GS, which occurs with the cases mounted, especially in partial and full load operation at speeds between 80 and 130 km / h. However, this is exactly the speed range in which you are most often on the move. Or the one you can least avoid. Some drivers report that the noise can cause discomfort on longer journeys. This was the reason for the developers at Wunderlich to investigate the phenomenon - which they knew from their own experience - from an engineering point of view, in order to then develop a functional solution that reduces and minimizes the effect.
The phenomenon and its cause
As part of test drives, the BMW specialists were able to identify the resonance chamber, which is roughly formed from the inside of the case and the entire rear wheel arch, as the secondary noise source. The rear silencer mounted on the right also protrudes into this space. The resonance chamber turns out to be a sound source due to its geometry, its volume and the materials (and their acoustic reflection behavior) that limit it. It is therefore not primarily mechanical vibrations, but rather the sound pressure directly escaping from the exhaust that stimulates the space described to resonate. This resonance space acts like a mechanical amplifier. He is the cause of the booming noise.
After this knowledge, it was also clear why the noise is particularly noticeable in the partial and full load range: These are the operating states in which the sound pressure level of the exhaust is physically the highest.
So it was necessary to switch off the described resonance space as a sound source. This could only be achieved if the sound pressure and the exhaust gas flow of the silencer were diverted or diverted. Conventional sound insulation has been ruled out at Wunderlich - because this is not practical.
Wunderlich exhaust deflector "GONZZOO"
Based on these findings, the developers considered a deflector solution from the start. The deflector should be designed in such a way that it deflects or shields the sound pressure of the original rear silencer in a targeted manner so that it does not even reach the resonance chamber and stimulates roaring. This defined the primary requirements of the specifications:
- The redirection of the sound pressure should provide a significant noise reduction at head height
from the driver and front passenger
- The shielding at the top and to the side should provide the additional positive effect,
that the sound waves are radiated downwards and backwards and therefore as less sound
- In the subjective perception when passing the GS should - depending on the
Free field conditions - a significant noise reduction can be achieved
- The deflector should shield the heat radiation of the exhaust gas flow so that the
The heating of the right case and the contents of the case are noticeably reduced
In addition to the challenges that arose from the demanding primary requirements, the Wunderlich developers paid special attention to other framework conditions. Because only those who manipulate an exhaust system in an unprofessional manner risk the expiry of the operating license. For this reason, Wunderlich's specifications included further technical requirements of major importance:
- The exhaust deflector should receive an ABE
- The solution should not affect the engine performance, in particular not negatively, i.e. affect the
Do not change the back pressure in the exhaust system compared to the series
- The solution should be simple and effective, especially when driving with mounted
- The solution should be flexible in use and be small in terms of geometry
With the now presented exhaust deflector "GONZZOO", Wunderlich has met all of the above requirements. It is model-specifically designed for the BMW R 1250 GS + Adventure and the BMW R 1200 GS LC + Adventure with the original silencer.
The »GONZZOO« - efficient, ingeniously constructed and with ABE
The Wunderlich »GONZZOO« deflector efficiently reduces the specific droning of the GS. And it reduces the noise pollution for the environment. This corresponds to the in-house Wunderlich BLAU sustainability initiative. The "GONZZOO" is remarkable because Wunderlich has succeeded in reducing it to the bare minimum. The physical and engineering know-how that is in it is easily misunderstood. Because the extensive preliminary investigations for the development of the effective deflector were complex.
Following the measurements taken by the Ringen company, TÜV Rheinland carried out its own series of measurements on the deflector as part of the technical tests for issuing the ABE. These extensive measurements prove that the permissible limit values for the sound pressure level of the original exhaust system are not changed. The completion of the administrative act at the KBA, which concludes the official issuing of the ABE for the BMW R 1250 GS (incl. Adventure) and the BMW R 1200 GS LC (incl. Adventure), is expected soon.
Always ready for use: The »GONZZOO« is compact and easy to stow away
A big advantage is that the »GONZZOO« is small and easy to stow away and always have with you. Thanks to the spring tensioner, it can be assembled or disassembled at any time and used anywhere (slip-on)! Wunderlich manufactures the »GONZZOO« exhaust deflector in Germany and will be offering it from February for all BMW R 1200 GS LC and R 1250 GS models at a price of € 79,90.
Photo / s: Wunderlich
At a glance:
20881-000 - Wunderlich exhaust deflector »GONZZOO« - stainless steel
• Suitable for BMW R 1250 GS + Adventure and R 1200 GS LC + Adventure with original
• The exhaust deflector »GONZZOO« ensures a significant noise reduction at head height
of driver and front passenger and minimizes the roar of the, which is often perceived as unpleasant
• Less noise ensures relaxed and safe driving
• No loss of performance
• In the subjective perception, the GS when driving past - depends on the
Free field conditions - notice a significant reduction in noise
• Shields the suitcase from the heat radiation of the exhaust gas flow and reduces heating
of the content
• Compact, effective construction
• Easy to store
• Precisely fitting, secure, simple assembly with spring hooks (slip-on)
• Including assembly tools
• ABE is pending
• Material: stainless steel, precisely processed
• Wunderlich premium product.
• Small series. Made by hand
• Design. Functional and integrated.
• 60 days right of return
• Made in Germany
• 5 years warranty
Is there a connection between noise reduction and ergonomics? Perception and its effects on safety! When riding a motorcycle, nothing should be irritating and thus distract from the joy of driving and the traffic. Wunderlich offers a huge range of ergonomic components that follow precisely this approach. They allow the motorcycle to be adapted so that nothing irritates or disturbs you and you can enjoy driving, but also see the traffic situation in advance, because all human-machine interfaces are optimal. So ergonomics not only creates a gain in comfort and driving pleasure, but - actually just as relevant - extra safety when riding a motorcycle.
The fact that what applies to an unergonomic motorcycle in the conventional sense can also be applied analogously to noise pollution. In addition to the purely objective exposure, noise pollution can cause subjectively perceived impairments to well-being that irritate and disturb when driving, so that the driver can no longer concentrate 100% on driving and the traffic situation. If you reduce noise pollution and its subjectively perceived impairment of well-being, you also gain a plus in driving safety and, above all, driving pleasure.
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